One of the common types of refuse collecting vehicles comprises an open, elongated rectangular body into which refuse is dumped near its front end, either by operators who actually empty refuse cans through a side door or by powered mechanisms which may raise large refuse containers and dump their contents into such a body. Many of these bodies are equipped with transversely extending ejector plates and have openable tailgates at the rear ends of the bodies. Such an ejector plate usually is actuated by an hydraulic cylinder which first moves the plate and the refuse rearwardly, to compact it against the tailgate, thus to reduce the space occupied, for example, by large cardboard cartons. After the tailgate is opened, the ejector plate is moved all the way to the rear of the body to eject a load of refuse from the body at a location such as a city dump.
When large volumes of refuse are dumped into a truck of this type the ejector plate usually is cycled, first to move the refuse backwardly to compact it somewhat and, when the resistance to further movement of the ejector plate backwards reaches a certain level, the controls are reversed to pull the ejector plate to the front of the body for the reception of additional refuse.
Because the resistance to compaction is a function of the area of the ejector plate acting against the entire mass of refuse in the vehicle body, it is the object of the instant invention to apply the same hydraulic force to a small portion of the ejector plate to extend such a "compaction plate" into the refuse to achieve further compaction.
It is therefore the principal object of the instant invention to provide an ejector plate mechanism which consists of a main, transversely extending ejector plate that is powered by a main hydraulic cylinder which acts between a forward part of the vehicle body and the ejector plate structure to move the ejector plate rearwardly for pushing the refuse to the rear of the truck and partially compacting it against the closed tailgate, the mechanism also including a compaction plate which is extended rearwardly relative to the main ejector plate when the resistance to further rearward movement of the ejector plate reaches a predetermined level.
It is yet another object of the instant invention to provide a transversely extending ejector plate powered by a hydraulic cylinder and including a compaction plate which is generally centrally located in the ejector plate and forms a part of the refuse contacting face of the ejector plate and which is pivotally mounted at its upper end to the ejector plate; the main cylinder being connected directly to the compaction plate and one or more secondary cylinders being connected between the ejector plate structure and the compaction plate; the hydraulic circuitry including a pressure relief valve which controls the flow of fluid to the secondary cylinders so that the compaction plate can be moved rearwardly relative to the main ejector plate when the resistance to the movement of the ejector plate reaches a predetermined level.
Other and more specific objects and advantages will become apparent from the specification which follows and from the drawings to be described below.